You Are the First to Arrive on the Scene of a Collapse

You are the first to arrive on the scene of a collapse of a balcony at an apartment building. You are met by a man whose arm is nearly severed, and you can see exposed bone and muscle tissue. Bleeding seems to be minimal. What is your next course of action?

A) This is a life-threating injury, so treat it immediately and call for additional resources.
B) This is an "open incident," so using START he is a "green" patient. Have him sit in a safe area, apply a basic dressing to control bleeding, and, if possible, find someone to monitor him. Perform the scene size-up and triage.
C) This is a "closed incident." Perform a scene size-up and treat this patient. Any other incoming units can continue treating people as they are found.
D) Take him to the ambulance.